1. Field of the Invention
Embodiments relate to transition metal doped Sn phosphate glass compositions and methods of making transition metal doped Sn phosphate glass compositions, and more particularly to transition metal doped Sn phosphate glasses useful for, for example, as sealing glasses.
2. Technical Background
Chemically durable, low temperature glasses are useful, for example, as frits or glasses in sealing applications. Lead-containing borate and borosilicate glasses have been the traditional materials for such applications. However, in view of the increasing demand for environmentally friendly materials, lead-free glasses having similar durability and sealing temperatures as the conventional glasses have become desirable. Several types of lead-free phosphate glasses for use as environmentally friendly or “green” frits, for example, SnZn and VSb phosphate glasses have previously been developed.
In order to have maximum flexibility in tailoring a potential sealing glass for a specific application, it would be advantageous to have as wide a range as possible of available glass compositions for sealing applications so that, for example, the thermal expansion coefficient or the softening point can be chosen for instance to match a particular substrate without compromising chemical durability. Further, it would be advantageous for such glass compositions to be lead-free.
Glass compositions, as described herein, address one or more of the above-mentioned disadvantages of conventional glass compositions useful for sealing applications and provide one or more of the following advantages: significant expansion of the glass forming region of “green” sealing glasses allows for greater flexibility in tailoring other glass properties, such as characteristic temperatures, thermal expansion coefficient, and/or refractive index that may be advantageous for specific applications, especially when an exact match with a particular substrate's properties is needed. The transition metal additives, for example, Ti, V, Fe, and/or Nb, may provide the additional benefit that, while they can enable further tailoring of properties such as thermal expansion, this tailorability may be achieved without sacrificing the desirable low characteristic temperature typically found in conventional SnZn phosphate glasses
One embodiment is a glass composition comprising in mole percent:
40 to 80 percent SnO;
12 to 35 percent P2O5;
0 to 15 percent ZnO; and
greater than 0 to 40 percent metal oxide, wherein the metal oxide is selected from titanium oxide, vanadium oxide, iron oxide, niobium oxide, and combinations thereof and
wherein when ZnO is present in an amount of 6 percent or more, and when the metal oxide is titanium oxide, niobium oxide, or a combination thereof, then titanium oxide, niobium oxide, or a combination thereof is present in an amount greater than 5 percent.
Another embodiment is a glass composition consisting essentially of in mole percent:
40 to 80 percent SnO;
12 to 35 percent P2O5;
0 to 15 percent ZnO; and
greater than 0 to 40 percent metal oxide, wherein the metal oxide is selected from titanium oxide, vanadium oxide, iron oxide, niobium oxide, and combinations thereof and
wherein when ZnO is present in an amount of 6 percent or more, and when the metal oxide is titanium oxide, niobium oxide, or a combination thereof, then titanium oxide, niobium oxide, or a combination thereof is present in an amount greater than 5 percent.
Another embodiment is a glass composition comprising in mole percent:
40 to 80 percent SnO;
12 to less than 25 percent P2O5;
0 to 15 percent ZnO; and
greater than 0 to 40 percent metal oxide, wherein the metal oxide is selected from titanium oxide, vanadium oxide, iron oxide, niobium oxide, and combinations thereof.
Another embodiment is a glass composition consisting essentially of in mole percent:
40 to 80 percent SnO;
12 to less than 25 percent P2O5;
0 to 15 percent ZnO; and
greater than 0 to 40 percent metal oxide, wherein the metal oxide is selected from titanium oxide, vanadium oxide, iron oxide, niobium oxide, and combinations thereof.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the invention as described in the written description and claims hereof.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed.